This invention relates to cultivated varieties of true breeding, stable intermediate ryegrass for use as a short lived, improved turfgrass on golf courses and other areas using seeded turfgrasses.
Annual ryegrass (Lolium multiflorum) and Perennial ryegrass (Lolium perenne) are the two most widely used turfgrasses in the world. Many varieties of each species have been developed. Perennial ryegrass is used as both a turfgrass and a forage grass. Annual ryegrass is used as a forage grass and a turfgrass, but there are no commercially available varieties of turf type annual ryegrass.
For many turf applications, a stable variety of Intermediate ryegrass if available would be desirable. Intermediate ryegrasses are crosses between annual and perennial ryegrass. This cross is relatively easy to make and has been frequently done. However, once the cross has been made, the resulting plants are not stable and true breeding, but revert to annual or perennial types.
For many southern golf courses planted with Bermuda grass, a standard practice is to overseed every fall with perennial ryegrass. Perennial ryegrass provides an outstanding turf cover during the cool winter months. However, perennial ryegrass is very persistent and does not easily die out and give way for the re-emerging Bermuda grass in the spring when warm weather returns.
Annual ryegrass, such as the variety xe2x80x98Gulfxe2x80x99, can also be used to overseed dormant Bermuda grass, but the turf quality is poor and not acceptable to most golf courses. However, annual ryegrass does die off quickly in the spring to make way for the re-emerging Bermuda grass.
What turf managers need for many applications is a cultivar that combines the turf quality and color of perennial ryegrass with the annual nature of annual ryegrass.
In northern turf areas, turf managers have long used annual ryegrass as a short-lived xe2x80x9cnursexe2x80x9d grass for quick establishment when mixed with Kentucky bluegrass or red fescue. The annual ryegrass establishes very quickly and stabilizes the soil with a very quick ground cover establishment. Unfortunately annual ryegrass is very competitive in establishment and a very undesirable appearing species as a turfgrass.
What northern turf managers need for xe2x80x9cNurse grassxe2x80x9d situations is an attractive fast starting short lived ryegrass that provides a high quality turf surface that allows early establishment but dies back to allow the slower establishing but long lived perennial grasses such as Kentucky Bluegrass and red fescue to then take over.
Crosses between annual ryegrass and perennial ryegrass have been made in attempts to develop Intermediate ryegrasses. Some varieties that have been developed include Oregreen, Transtar, Froghair, Interim and Transit. To date, none of these varieties of Intermediate ryegrass have been stable and true breeding. These intermediate rye grass varieties have all reverted to annual ryegrass during seed production increase since they have not been stable and true breeding.
Eight Species of the genus Lolium have been described. All but L. perenne have an annual life cycle, or at least are very short lived perennials. The genus Lolium is not complicated with naturally occurring polyploids; all species are diploid. Worldwide, L. perenne and L. multiflorum, are the most important species of the genus. Common names are perennial ryegrass for L. perenne, and Italian or annual ryegrass for L. multiflorum. 
L. perenne and L. multiflorum hybridize readily. In fact, natural and bred hybrids among the three outcrossing ryegrass species, L. multiflorumxc3x97L. perenne (=L.xc3x97hybridum), L. multiflorumxc3x97L. rigidum; and L. perennexc3x97L. rigidum, have been reported in Australia and Europe. Sufficient crossing occurs between the outcrossing Lolium species to form a wide range of fertile hybrids.
A seedling root fluorescence (SRF) test has been the official method for separation of ryegrass kinds of the International Seed Testing Association (ISTA) since 1953 (Jones, 1983, ISTA, 1966). The routine use of the seedling root fluorescence test in the United States started approximately in 1941. This policy provided that a SRF test shall be made on all ryegrass samples for which the species is to be determined. After experimenting with various light sources, test length, and the lifting of seedlings, standard procedures for conducting fluorescence tests were proposed. The extracted pigment responsible for root fluorescence in annual ryegrass is a weak, basic alkaloid, only slightly soluble in water. It was named annuloline. Other tests have been used to attempt a more conclusively way to separate the two important ryegrass species. Morphologically, leaf vernation differences between perennial and annual ryegrass have been used. Other methods applying biochemical characters, such at electrophoresis on general seed proteins and isozymes have yielded good results. Like the SRF test, however, such alternative tests have not been supported by genetic linkage studies.
On a morphological test basis, leaf vernation is considered to be the most accurate seedling characteristic used for distinguishing annual from perennial ryegrass. The Oregon Seed Trade Association (OSTA) considered using this character as a supplement to the fluorescence test when monitoring seed lots for certified status.
Little mention is made of Intermediate ryegrass in the ryegrass literature. For example, the 1995 OECD List of Cultivars Eligible for Certification in 1995 lists over 200 varieties of Perennial Ryegrass and Annual Ryegrass but no varieties of Intermediate ryegrass. The inherent instability of Intermediate ryegrass has made the development of these type of ryegrasses very difficult.
In the description and tables which follow, a number of terms are used. In order to provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided:
Annual Ryegrass: Lolium multiflorum. A grass species commonly used as a turf grass that lives for one year or less.
Perennial Ryegrass: Lolium perenne. A grass species commonly used as a perennial turfgrass in the north and as a short-lived (less than one year) turfgrass to overseed warm season grasses.
Intermediate Ryegrass: Lolium hybridum. A grass species developed by crossing annual and perennial ryegrass. This is a xe2x80x9cman-madexe2x80x9d species which is not found in nature.
Turf: A covering of mowed vegetation usually a turfgrass, growing intimately with an upper stratum of intermingled roots and stems.
Turfgrass: A species or cultivar of grass, which is maintained as a mowed turf.
Turf Color: The composite visual color of a turfgrass community as perceived by the human eye. Usually measured on a 1 to 9 scale, with 9 being darkest.
Turf Quality: The degree to which a turf conforms to an agreed standard of uniformity, density, texture, growth, habit, smoothness, and color, as judged by subjective visual assessment. Usually measured on a 1-9 scale, with 9 being best.
Turfgrass Density: The number of turf grass tillers or shoots per unit area and measured at a certain time (e.g., days) after seeding.
Turfgrass Environment: The complex of climate, endaphic, biotic, and cultural (management) factors that act upon a turfgrass community and ultimately determine it""s form and survival.
True Breeding: As used herein, the term xe2x80x9ctrue breedingxe2x80x9d means the ability of a variety to produce seed for three or more generations that reproduces the described characteristics of the variety and meets accepted Standards of Uniformity as defined by the Oregon State Seed Certification Handbook 2000 (Seed Certification Handbook 2000, Oregon State University Certification Board, Oregon State Extension, pp 1-5, (2000))
Leaf Texture: The relative fineness or coarseness of turfgrass leaves measured in millimeters at the cut or mowed leaf blade and measured at 6 weeks after seeding.
Flag Leaf Width: The width of a flag leaf blade measured at the ligule.
Flag Leaf: The first leaf below the seed head.
Plant Height: The height of a fully headed unmowed plant measured from the ground to the tip of the tallest seed head.
Seed Size: The relative size of seeds usually measures by determining the number of seeds per pound.
1000 Seed Weight: A standard measurement for seed determined by weighting 1000 pure, whole, seeds of a variety.
Seedling Vertical Growth Rate: The vertical growth rate of seedlings determined by measuring the height of the longest expanded leaf (tallest leaf) and measured at 6 weeks after seeding.
Munsell Color Chart: The Munsell System of color notation is essentially a scientific concept for describing and analyzing color in terms of three attributes called Hue, Value, and Chroma. These attributes are arranged in orderly scales of equal visual steps. a) Hue: Chromatic colors in the system are divided into five principal classes, which are given the Hue names of red, yellow, blue, and purple. A further sub-division yields the five intermediate Hue names of yellow-red, green-yellow, yellow-blue, etc., these being combinations of the five principal hues. For even finer sub-division each of these ten hues is divided into ten steps each (1 Red to 10 Red, etc.) thus increasing the hue range to 100. Hence the Hue notation of any color indicates its relationship to the five principal and five intermediate Hues. It is written as a capital letter (R for red, etc.) preceded by its appropriate number. b) Value: The value notation indicates the degree of lightness or darkness of a color in relation to a neutral gray scale, which extends from a theoretically pure black symbolized as xe2x80x9c0/xe2x80x9d to a theoretically pure while symbolized as xe2x80x9c10/xe2x80x9d. A gray or a chromatic color that appears visually halfway in lightness between pure black and pure white has a value notation of xe2x80x9c5/xe2x80x9d. Lighter colors are indicated by numbers ranging above five while darker colors are indicated by numbers below five. c) Chroma: The Chroma notation of a color indicates the strength (soluration) or degree of departure of a particular Hue from a neutral gray of the same value. The Chroma scale extends from xe2x80x9c/0xe2x80x9d for a neutral gray out to 10, 12, 14 or farther, depending upon the saturation of that particular color.
The new intermediate ryegrass varieties of this invention are uniform and stable, and also have a plant height, leaf texture, flag leaf length, seedling vertical growth and turf density that is more similar to perennial ryegrass versus other previously available intermediate and annual ryegrasses. These characteristics provide a uniform, true breeding and overall superior intermediate ryegrass for turfgrass purposes.
Varieties of the invention can be produced from seed. The invention includes seed producing an intermediate ryegrass variety selected from the group including or consisting of Transist, A-97 and A-98. Such seed includes seed that has been deposited in the American Type Culture Collection.